1. Field of the Invention
The present invention relates to various fields such as the food processing, marine product, food hygiene, medical care and analytical instrument industries or the like.
2. Description of the Related Art
Histamine (Hm) is one of amines. It has a molecular formula of C.sub.5 H.sub.9 N.sub.3, a molecular number of 111, and a chemical structure represented by the formula (1). Histamine is not present in fresh fish, mollusk and meat. However, when they are contaminated by a microbe which has a strong histidine decarboxylase activity, histamine is produced as a toxic substance from histidine of a free amino acid in a protein organization due to a decarboxylating reaction shown in the formula (1). ##STR1##
When a food containing a large amount of histamine is ingested, an allergy-like poisoning is caused. The symptom of flushing appears on a face or the like from several minutes to several hours after meal, and followed by itching, urticaria, and eczema. In the worst case, the urticaria spreads all over the body and causes bronchitis and hypotension, thereby sometimes inviting a death.
It is generally said that bluefishes of red meat such as mackerel, skipjack, tuna, sardine, horse mackerel, etc. and beef or the like contain a large amount of free histidine, and easily cause a histamine poisoning. However, histamine poisonings caused by other protein food are also reported [D. E. Kramer et al. Seafood Quality Determination, 235-244, Elsevier Science Publishers B. V. Amsterdam (1986)].
It is pointed out that many histamine poisoning incidents occur in a region like Japan where a large amount of fish and mollusk are eaten.
In order to prevent the poisoning incidents, it is required to give care in particular to freshness and quality of fish and mollusk. Even if any abnormality can not be confirmed from a functional finding of fish and mollusk, 100 to 500 mg/100 g of an extremely large amount of histamine is sometimes contained therein. The control therefor is very difficult.
In Japan, a K value of decomposition rate of nucleotide is widely used as a freshness index of fish and mollusk, while the United States Food and Drug Administration (F.D.A.) has adopted histamine restriction (U.S. Federal Register in Sep. 4, 1982). If 10 to 20 mg histamine/100 g of meat in canned tuna is found, some action is officially taken. If not less than 50 mg of histamine is found, it is regarded as toxic for health. Thus, AOAC official method of analysis based on a fluorescent measurement has been established [W. F. Staruszkiewicz, et al., J. Assoc. Off. Anal. Chem., 60, 1125-1130 (1977)].
This fluorometric analysis is recognized as the most suitable method for determination of histamine contained in fish and mollusk. Similar methods are also employed in Europe. These analytical methods all use o-phthalaldehyde as a fluorescent reagent which yields a fluorophore by a condensation reaction with histamine. The intensity of the fluorophore is measured by a photofluorometer. However, before the condensation reaction, it is required to clean a sample by removing inhibitory constituents to the reaction. Therefore, means and time required for carrying out an anion exchange resin column treatment or a cation exchange resin column treatment or the like are inevitable.
Many studies of determination of histamine by a chromatography have been made. A thin-layer chromatography and a paper chromatography are relatively inexpensive measuring device and can measure simultaneously many samples, while an accuracy of determination is not sufficient. Further, it is pointed out that since nonvolatile amines like histamine can not be directly determined by a gas chromatography, there is an inconvenience of converting it into heptafluorobutyl derivatives before determination thereof.
In Japan, the determination by a high performance liquid chromatography (HPLC) is recognized as the most suitable method as described in Standard Methods of Analysis for Hygienic Chemists. Recently Yamanaka et al. have made a study of determination of histamine in red meat fish by the method of HPLC [J. Food Hygienic Soc. Jap. 30, 397-400 (1989)]. The result was scientifically excellent, since seven species of amines yielded simultaneously were successfully separated for determination with high sensitivity. However, this HPLC method requires a high order device and it takes one hour to operate the chromatography. These are problems for wide use of this method.